The goal of this line of research is to add to the existing body of literature on the effect of heat treatments on the microstructure of chrome-bearing white irons and add bend test data to the literature concerning chrome-bearing white irons. This project was intended to support an existing line of research into cast metal-ceramic lattices using chrome white iron as a substitute for sintered ceramic tiles used to defeat projectiles. Chrome-bearing white irons have a substantial quantity of chromium carbides, giving them high hardness and abrasion resistance. Additionally, tiles cast from white iron proved to be more durable than sintered ceramic tiles, breaking into large chunks rather than a powder following an impact. These properties make tiles cast from chrome-bearing white iron a low-cost alternative to sintered carbides. The alloy investigated contained nominally 14 chromium and 3.2 carbon by weight percent. Three-point bend test specimens were cut from cast plates. These specimens were austenitized, air cooled, then tempered prior to three-point bend and hardness testing. The microstructure of the specimens was evaluated using optical microscopy, SEM, and XRD. This line of research revealed that lower austenitization temperatures resulted in a martensitic matrix with fewer, smaller secondary carbides, resulting in higher strength and hardness. In contrast, higher austenitization temperatures produced an austenitic matrix with coarser carbides, resulting in lower strength and hardness. This research did not reveal an appreciable change in ductility over heat treatment temperature. / Master of Science / This research investigates a hard iron alloy capable of replacing expensive ceramics in situations where the goal is to prevent penetration by a projectile. This iron alloy, known as white cast iron, can be cast using typical foundry practices, making it cost-effective. Additionally, the properties can be changed by heat-treatment, a process that involves heating the material to a given temperature, holding it at that temperature for a given amount of time, then cooling the material at a given rate. The results of this research add to the existing understanding of how heat treatment affects the properties of white cast iron. Additionally, this research generated new data about the strength of white cast irons in a three-point bending test, a test not normally used for white cast irons. The research found that high heat-treatment temperatures resulted in a softer white cast iron with lower strength. The structure of the white cast iron treated at these temperatures was predominantly austenite, a soft iron phase, and large carbides, a hard but brittle phase. Temperatures close to the lower end of the temperature range tested resulted in a harder white cast iron with higher strength. The structure of the iron in these conditions contained martensite, a hard iron phase, some austenite, and smaller but more angular carbides.

Desert mule deer (Odocoileus hemionus crooki) abundance and distribution, deer activity and diet, fawn survival, and predation were studied in Big Bend National Park, Texas from 15 January 1980 to 9 December 1981. Deer abundance was correlated with total plant, forage, and succulent densities but was also related to perennial water abundance and bed site availability. Fawn production and survival were related to spring rainfall. Diurnal and annual deer activity were influenced by temperature where spring and winter had longer daily activity compared to summer. Daily activity by deer was highest during the morning and evening. Forage use varied seasonally with browse use decreasing from spring to winter with a corresponding increase in use of forbs. Diets of two deer herds were compared and during drought periods forb use decreased until summer rains occurred. Prior to the rains, deer relied on evergreen browse species. Additionally, deer within mesic areas had a higher use of forb species contrasted with deer within xeric areas. Predator diet significantly changed with a decline in the deer population determined from pellet-group transects. Mountain lions (Felis concolor) used smaller prey including javelina and lagomorphs. Coyotes (Canis latrans) fed opportunistically by increasing use of insects, birds, reptiles, and lagomorphs. Bobcats (Lynx rufus) increased use of lagomorphs with little change in other prey species. Given alternate prey species, predator populations remained relatively constant given the deer decline.

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During the New Deal, the Civilian Conservation Corps (CCC) put young men to work in state and national parks across the United States. One of such parks, Big Bend National Park, is the focus of this study. The CCC had two camps within the park, one from 1934 to 1937 and another from 1940 to 1942. During their time in Big Bend, the CCC constructed many projects including a road, trails, cabins, and other various structures. The purpose of this study is to delineate the role of the CCC in creating Big Bend National Park and the experience of the CCC during their time in the Big Bend camp. This study determines the role of the CCC through a discussion of the planning done by the CCC for Big Bend National Park and the work completed by the CCC in the park. In doing so, it argues that the CCC played a substantial and significant role in the development and character of the park. This study works to understand the experience of the CCC in Big Bend through a discussion of education, safety, and an investigation of a commanding officer. Through this discussion, the role of the federal government and national organization in the local camps can be seen, as can the value they placed in the enrollees.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This paper, evaluates a proposal for an external bend fluvial erosion control, using submerged vanes as velocity and shear stress control, verifying its effectiveness by modeling in Iber to calculate the scour produced by discharges with different return periods. The results indicate that the velocity, shear stress and scour decrease along the curve, due to submerged vanes.

Within Big Bend National Park, the unconformable contact between the Buda Limestone and the overlying Boquillas Formation represents the Commanchean-Gulfian boundary. Previous studies of the geochronology of this interval have relied primarily on provincial ammonite faunas rather than foraminifera, and place the Buda and basal Boquillas in the Lower Cenomanian. Because of its indurated nature, a comprehensive foraminiferal biozonation has not been acquired for the Buda Limestone. Recent revisions to Cretaceous foraminiferal biozonations and taxonomies necessitates a new biostratigraphic study of the Buda - Boquillas interval. The overlapping ranges of F. washitensis, G. bentonensis, G. caseyi, P. appenninica, P. delrioensis, P. stephani, and R. montsalvensis place the Buda within the upper portion of the Early to Middle Cenomanian Th. globotruncanoides Zone. Microkarst found on the surface of the Buda Limestone has been interpreted as representing a subaerial exposure and sequence boundary. However, microkarst-like features can result from subaqueous or intrastratal processes. Carbon and oxygen stable isotope analysis of the lower and middle Buda has indicated a mean δ13C value of 1.73‰ VPDB, which is in line with other values reported from the Lower Cenomanian. The top 2.6m of Buda contains a 0.62‰ negative δ13C shift from 1.88‰ VPDB to 1.26‰ VDPB in a 40 cm interval, expected if subaerial exposure occurred. Higher variation in measured carbon isotope values beneath the contact also lend evidence for meteoric alteration. The standard deviation in δ13C values from the top 2.8 m of the Buda is 0.207, which is 2.16 times larger than the rest of the studied section at 0.096. The Buda contains a shallow pelagic-dominated fauna of heterohelicids (45-90%), globigerinellids (3-37%), and hedbergellids (4-22%). Intermediate-depth globigerinellids display an initial increase followed by a marked decrease in abundance upsection, interpreted as sea level transgression and regression, respectively. The lower contact of the Buda with the Del Rio Clay has been previously interpreted as a subaerial exposure, and a P:B break from ~0% planktonics in the upper Del Rio to ~80% in the Buda supports this claim. This study therefore interprets both the upper and lower contacts of the Buda as sequence boundaries. The overlying 1.2 m Boquillas is nearly devoid of benthics and represents a deeper assemblage including the double-keeled Dicarinella sp., as well as several Upper Cenomanian (D. algeriana Subzone) species. Based on foraminiferal data, the duration of the Buda - Boquillas unconformity is roughly equivalent to the missing Th. reicheli and Th. greenhornensis Biozones, or a sizable portion of the Middle Cenomanian. / Systematic paleontology -- Biostratigraphy of the Buda Limestone -- Biostratigraphy of the lowermost Boquillas Formation -- Stable isotope geochemistry. / Department of Geological Sciences

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Pattern recognition is very important in automatic industry. The automation machinery vision system must exchange information very fast with the object we need. So the machinery vision system must have powerful recognition ability. There are more important on image processing, lately. But most researches of image processing are developed on high-resolution image. However, in same situation, for increasing the processing speed, reducing the saving space. Low-resolution image are the only way to achieve the above condition up to now. For the purpose of quickly recognition, we construct the recognition system on low-resolution image. From observing the characteristic of hexagonal grid, we knew the hexagonal grid have greater angular resolution and better image performance than rectangular grid. Therefore, we apply the hexagonal grid on low-resolution image, and using Curve Bend Function (call CBF) on hexagonal gird system; for promoting the accuracy of recognition.We presented an technique of subpixel on low-resolution hexagonal image to obtain better results.

Previous work in our laboratory indicates that the diameter of brain arteries and arterioles can be increased by N-methyl-D-aspartate (NMDA) receptor activation. We looked for expression of NMDA receptors and endothelial cell responses to NMDA receptor agonists and antagonists in the mouse brain endothelial cell line bEnd.3. Using RT-PCR and Western blotting we found evidence supporting the presence of NMDA receptor subunits NR1 and NR2C. Treatment of bEnd.3 cells with combinations of 100 μM glutamate and D-serine significantly increased intracellular calcium. However, we saw no direct evidence that NO was produced in response to NMDA receptor activation using the Griess method. We did observe an NMDA receptor-dependent increase in protein nitrosylation. This increase is unlikely related to enhanced NO levels since it was not correlated with NO production and was not inhibited by the endothelial NO synthase inhibitor L-NIO.

Water hammer represents a complex hydraulic phenomenon with significant consequences on the proper functioning and safety of operation for pipe and conduit systems. The complexity and intricate physics of water hammer translated into significant difficulties associated firstly, with finding a proper solution for understanding the mechanism of its occurrence and, secondly, relating to proposing technically and economically viable design methods and devices that would help reduce and mitigate water hammer effects. In this context, the present thesis deals with the numerical modeling of the transient behaviour of water pipe segments. Following an extensive literature review of the state-of-the-art on the water hammer mechanisms and past work on experimental, analytical and numerical analysis of this phenomenon, a three dimensional numerical model of the water hammer in a pipe which considers the fluid-structure interaction (FSI) is developed using a Finite Element Method – Finite Volume Method (FEM-FVM) technique. Structural and fluid computational results based on rapid and slow gate closure scenarios are compared with existing closed-form solutions of the water hammer. A parametric study is also performed on a simply supported pipe segment to determine the influence of various design parameter. A systematic sensitivity analysis was conducted and a ranking mechanism was established for the importance of each parameter on the fluid fields and structural response. A first comparative analysis is conducted on horizontally and vertically bent elevated pipe segments to quantify the influence of the bend angle on the results. A second comparative analysis is performed on a horizontally bent segment buried in soil to determine the influence of the pipe interaction with the soil on the response. It is observed that the thickness, span, initial velocity and bend angle had a significant impact on the pressure and structural response. The presence of soil was observed to have a significant benefit in decreasing the von-Mises stresses.